On a daily basis, people are exposed to potentially harmful noises in their environment, such as the sounds from television, traffic, construction, radio, and industrial appliances. Normally, people hear these sounds at safe levels that do not affect their hearing. However, when people are exposed to harmful noises that are too loud or of prolonged duration, hair cells in the inner ear can be damaged, causing noise-induced hearing loss (NIHL). The hair cells are small sensory cells in the inner ear that convert sound energy into electrical signals that travel to the auditory processing centers of the brain. Once damaged, the hair cells cannot grow back. NIHL can be caused by a one-time exposure to an intense impulse or burst sound, such as an alarm, or by continuous exposure to loud sounds over an extended period of time.
In the mobile electronic age, people are frequently exposed to noise pollution from cell phones (e.g., incoming phone call sounds), portable media players (e.g., message alert sounds), and laptops (e.g., audible reminder prompts). Moreover, headphones and earpieces are directly coupled to the person's ear and can thus inject potentially harmful audio at unexpected times and with unexpected levels. Furthermore, with headphones, a user is immersed in the audio experience and generally less likely to hearing important sounds within their environment. In some cases, the user may even turn up the volume to hear the audio over the background noises. This can put the user in a compromising situation since they may not be aware of warning cues in their environment as well as putting them at high sound exposure risk.
Although some headphones have electronic circuitry and software to limit the level of audio delivered to the ear, they are not generally well received by the public as a result. Moreover, they do not take into account the person's environment or the person's hearing sensitivity. A need therefore exists for enhancing the user's audible experience while preserving their hearing acuity in their own environment.